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Thread: Electric fields composition

  1. #1
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    Electric fields composition

    We know magnetic fields are made of virtual photons. Then what are electric fields made of?

  2. #2
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    We don't really say that magnetic fields are made of virtual photons.

    In QED the electromagnetic field is the fundamental entity and photons (virtual and otherwise) are excitations within it. There are not seperate electric and magnetic fields - they are both manifestations of the underlying phenomenon of an electromagnetic field. That is demonstrated neatly by the relativistic result that effects nominally assigned to be from an electric field is seen as resulting from a magnetic field (or mixture of fields) for other observers.

  3. #3
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    Quote Originally Posted by Shaula View Post
    We don't really say that magnetic fields are made of virtual photons.

    In QED the electromagnetic field is the fundamental entity and photons (virtual and otherwise) are excitations within it. There are not seperate electric and magnetic fields - they are both manifestations of the underlying phenomenon of an electromagnetic field. That is demonstrated neatly by the relativistic result that effects nominally assigned to be from an electric field is seen as resulting from a magnetic field (or mixture of fields) for other observers.
    Ah ok. Thanks,

  4. #4
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    philippeb8, It might be helpful to play around with some apparatus to clarify concepts. It firms up conceptual thinking. A friend took out a long piece of copper wire in a large classroom...about 25 feet long. He hitched it up to a galvanometer, which measures sensitive currents. The he had two students swing it like a jump rope, in a loop. In some orientations a current was observed because of the cutting of field lines of the Earth. On other orientations ...nada. You could use it to slowly charge your cellphone. No plugs. No batteries. Had to be the right orientation though. Think about that. pete

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